In die cylinders, whether of the stand-alone type or those in manifold systems, it is necessary from time to time to repair and/or replace the piston seal. This has required a complete dismantling of the die cylinder in order to gain access to the piston seal. What is needed is a cylinder and piston construction in which the piston can be easily and quickly removed from the cylinder when and if repair or replacement of the piston seal is required.
In accordance with the present invention, a removable sealing cartridge is provided between the piston and the cylinder. The piston is capable of being separated from the cylinder when the cartridge is removed. The cylinder is free of any obstructions which would interfere with withdrawal and the separation of the piston.
More specifically, the piston seal is on an inner end portion of the piston. A removable sealing cartridge is provided between an outer end portion of the piston and an outer cylinder portion. The piston is capable of full axially outward retraction and separation from the cylinder when the cartridge is removed. Preferably the sealing cartridge is seated on a shoulder between inner and outer cylinder portions and is removably retained on the shoulder by a snap ring. The piston is so dimensioned that it may be easily withdrawn axially outwardly from the cylinder.
Preferably the cartridge comprises a first support ring seated on the shoulder and a second support ring seated on the first support ring. Sealing means are provided to seal against one of the support rings and against the outer end portion of the piston. Additional sealing means seals against the outer cylinder portion. Preferably the sealing means which seals against one of the support rings and against the outer end portion of the piston comprises first and second sealing rings which seal against the outer end portion of the piston and against the second support ring, with a ring separator between the first and second sealing rings.
One object of this invention is to provide a die cylinder, either of the stand-alone type or in a manifold system, which has the foregoing features and capabilities.
Another object is to provide a die cylinder including a sealing cartridge which is composed of a relatively few simple parts, is rugged and durable in use, is capable of being inexpensively manufactured, and can be easily and quickly assembled and disassembled.